Dual windup extensional rheometer

Abstract

An extensional rheometer comprises a drive shaft connected to an armature, wherein the armature is further connected to a torque shaft, and two rotatable drums are mounted in the armature. One end of a sample is connected to each drum, and the drums are rotated, stretching the sample until the sample breaks. The torque in the apparatus caused by the stretching of the sample is measured. Environmental control may be provided for testing samples under different conditions.

What is claimed is:  
     
       1. An apparatus for measuring the extensional deformation rate of a sample, comprising: 
       (a) a drive shaft attached to an armature wherein the armature is further connected to a torque shaft that does not move;  
       (b) primary and secondary rotatable drums in proximity to one another, wherein said primary and secondary drums are mounted in said armature whereby said drive shaft rotates said primary and secondary drums in opposite directions of rotation; and  
       (c) torque transducer means activated by the torque shaft for measuring the torque created on the torque shaft by said armature in response to the rotation of the primary and secondary drums.  
     
     
       2. The apparatus of  claim 1  wherein said primary and secondary drums are in substantially parallel alignment, are mounted on bearings, and have associated therewith means for directing a windup of the sample on said primary and secondary drums. 
     
     
       3. The apparatus of  claim 2  wherein the means for directing the windup of the sample is helical threading on each of said primary and secondary drums. 
     
     
       4. The apparatus of  claim 1  wherein said primary and secondary drums are geared to be counter rotating. 
     
     
       5. The apparatus of  claim 2  wherein the means for directing the windup of a sample is helical threading on each of said drums. 
     
     
       6. The apparatus of  claim 3  wherein each of said primary and secondary drums is geared and said gears intermesh such that said drums rotate at the same speed. 
     
     
       7. The apparatus of  claim 1  wherein each said primary and secondary drums has securing means for securing the sample thereto. 
     
     
       8. The apparatus of  claim 1  wherein the armature is disposed in an environmental chamber. 
     
     
       9. A method for measuring the rate of flow of low modulus solids comprising the steps of 
       (a) providing an apparatus for measuring the rate of extensional flow of low modulus solids comprising, a drive shaft mounted in an armature wherein the armature is further connected to a torque shaft, and mounted in the armature are two rotatable drums in proximity to one another, wherein a first said drum is mounted in said armature substantially in alignment with said torque and drive shafts, and a second said drum is adjacent thereto  
       (b) fixing a sample to both said drums, one end of said sample being attached to each said drum  
       (c) causing the two ends of the sample to be pulled away from each other by rotation of the drums, and  
       (d) measuring the torque created in the torque shaft by the drawing of the sample.  
     
     
       10. The method of  claim 9  which comprises the further steps of 
       (a) measuring the maximum torque achieved by the sample, and  
       (b) measuring the time elapsed from the start of the measurement to breaking of the sample.  
     
     
       11. The method of  claim 9  which comprises the further steps of disposing said first and second drums in substantially parallel alignment, mounting said drums on bearings, and associating therewith means for directing the windup of a sample on said drums. 
     
     
       12. The method of  claim 9  which comprises the further step of gearing said drums to be counter rotating. 
     
     
       13. The method of  claim 9  which comprises the further step of providing each said drum with gearing and causing said gears to intermesh such that said first and second drums rotate at the same speed. 
     
     
       14. The method of  claim 9  which comprises the further step of providing each said drum with securing means for securing a sample thereto. 
     
     
       15. A method for measuring the measuring the extensional deformation rate of a sample comprising the steps of 
       (a) providing an apparatus for measuring the extensional deformation rate of a sample comprising, a drive shaft mounted to an armature wherein the armature is further connected to a torque shaft, and mounted in the armature are a primary rotatable drum and a secondary rotatable drum, said primary and secondary rotatabale drums being in proximity to one another, wherein the primary drum is mounted to said armature substantially in alignment with said drive shaft;  
       (b) fixing the sample to said primary and secondary drums, one end of said sample being attached to said primary drum and another end of said sample being attached to said secondary drum;  
       (c) causing the ends of the sample to be pulled away from each other by rotation of the primary and secondary drums, and  
       (d) measuring the torque created in the torque shaft by the ends of the sample being pulled away from each other by windup of the sample on the drums.  
     
     
       16. The method of  claim 15  which comprises the further steps of 
       (a) measuring the maximum torque achieved by the sample, and  
       (b) measuring the time elapsed from the start of the measurement to breaking of the sample.  
     
     
       17. The method of  claim 15  which comprises the further steps of disposing said primary and secondary drums in substantially parallel alignment, mounting said drums on bearings, and associating therewith means for directing the windup of the sample on said drums. 
     
     
       18. The method of  claim 15  which comprises the further step of gearing said drums to be counter rotating. 
     
     
       19. The method of  claim 15  which comprises the further step of providing each of said drums with gearing and causing said gears to intermesh such that said primary and secondary drums rotate at the same speed. 
     
     
       20. The method of  claim 15  which comprises the further step of providing said primary and secondary drums with securing means for securing a sample thereto.